1. Field of the invention
The present application relates to a device utilized in the specialty of orthodontics and more particularly to an orthodontic bracket used in fastening orthodontic arch wires to a tooth so that the tooth may be properly positioned within the dental arch. In addition, the present application relates to an orthodontic edgewise arch bracket locking mechanism which includes a handle and a locking hook which are pivotally secured to each other and to two of the tie wings of a conventional edgewise arch bracket. The handle, locking hook and the two tie wings are privotally positioned in an over-center arrangement so that when the locking hook is positioned adjacent to the other tie wings and the handle is moved to a position parallel to the body of the arch bracket, the locking hook is snapped in a cam-like action against the bracket body holding an arch wire firmly within a slot in the bracket body.
2. Description of the Prior Art
Heretofore, the most popular and universally employed orthodontic appliance has been the edgewise arch. For nearly fifty years, an arch wire has been secured to a bracket portion of the edgewise arch to properly position certain teeth within the dental arch. The arch wires of the prior art were secured to the bracket portion by means of thin ligature wires or tiny elastic members secured to the four tie wings of an arch bracket. Securing these prior art ligature wires required the following steps:
A. sliding the ligature wire under the four tie wings of an arch bracket; PA1 B. twisting the ligature tightly over the arch wire; PA1 C. cutting the excess ligature leaving a small twisted pig-tail, and PA1 D. tucking the pig-tail under the arch wire to prevent laceration of a patient's lips, check or tongue.
To remove these prior art ligature wires necessitated carefully cutting the ligatures with very sharp nippers and removing the remnants. This procedure was sometimes dangerous to the aforementioned tissues.
The use of prior art tiny elastic members required the careful spreading of the members so as to fit over the four tie wings of an arch bracket. The disadvantages of these members included an inability to retain an arch wire firmly within the entire slot of an arch bracket, unless the wire itself conformed to the slot in a passive state. It is known that the flexibility of the arch wire is the most efficient means of transmitting a corrective force through the bracket and thus to the tooth itself. It is of paramount importance that the arch wire be secured to the arch bracket and fully seated in the bracket slot when the arch wire is in an active state. Prior to the present invention, the proper securement of the arch wire was only accomplished by use of ligature wires. Elastic members were never fully satisfactory to secure the arch wire.
In addition, since both wire ligatures and elastic members frictionally grip the arch wire, they do not readily permit sliding of the arch brackets and teeth along the arch wire, which is an important exigency in certain phases of orthodontic procedures.
Other prior art devices were designed to overcome the disadvantages of the use of wire ligatures and elastic members. One prior art device, U.S. Pat. No. 3,748,740 issued to A. J. Wildman, was designed to retain one or more arch wires in a groove by means of a self-latching, C-shaped hook. This prior art device was a complete departure from the conventional edgewise bracket including tie wings used by most orthodontists. Since the Wildman device was such a drastic departure from the traditional edgewise bracket, it is not believed that a conservative and doctrinaire edgewise orthodontist would utilize this device.
Another prior art device, U.S. Pat. No. 3,574,942 issued to J. B. McCabe, was designed to retain an arch wire within a recess by means of a lateral projection which may be rotated into the retaining position. Again, this device was a complete departure from the conventional edgewise bracket including tie wings.
Still another prior art device, U.S. Pat. No. 3,205,577 issued to J. A. Linde, was designed to releasably lock the rear support of an orthodontic appliance against lateral movement while permitting the appliance to have free longitudinal movement. While this device apparently shows a locking mechanism, it was not intended to be used with a conventional edgewise bracket as in the present invention.